Design and manufacturing of semiconductor devices requires cooperative application of a number of diverse technologies. On a macro-scale, a number of these technologies are aimed at first creating the semiconductor devices. Another group of technical disciplines is aimed at packaging the devices. As devices become more complex and need to be integrated with additional devices and other apparatus, a universal interconnection scheme becomes more difficult.
Typically, a semiconductor device has fixed input/output (I/O) lines and interconnection with an external package can be difficult. This difficulty may lead to a redesign of an entire integrated circuit to avoid long lead wires from the device to the package. Additionally, any lead lines that cross over each other have a potential for developing an electrical short. Therefore, the interconnection of semiconductor devices with device packages is a major challenge in the art.
The process of packaging semiconductor devices typically starts with a substrate that is, for example, ceramic, plastic, or a metal leadframe. The devices are mounted on the surface of the substrate and layers of interconnect lines and vias are formed that connect the devices to surrounding circuitry. Many different packaging approaches are known and have been used for mounting and interconnecting semiconductor devices, such as Dual-In-Line Packages (DIP), Pin Grid Arrays (PGA), Plastic Leaded Chip Carriers (PLCC) and Quad Flat Packages (QFP). Multi-layer structures have further been used to connect physically closely spaced integrated circuits with each other. The chip wiring contains layers of interconnect metal that are interconnected with interconnect vias, layers of dielectric (such as polyimide), or insulating layers separate metal layers that make up the interconnect network and the vias and contact points that establish connections between the interconnect networks. The design of overlying and closely spaced interconnect lines is subject to strict rules of design that are aimed at improving package performance despite a high density packaging that may be used. For example, electrical interference between adjacent lines is minimized or avoided by creating interconnect lines for primary signals that intersect under 90 degree angles.
The active component or device integration and densification process in integrated circuits has motivated a continuous and ongoing migration of interconnect wiring and connections from boards, cards, and multichip modules to the chip itself. A surface of the chip, with its multilayer wiring, has become a microcosm of the conductor and insulator configurations that were common on previous multilayer printed-circuit boards and multilayer ceramic packages. A logic chip with 700 circuits and three layers of wiring has approximately 5 m of aluminum wiring on a chip less than 5 mm square. There are over 17,000 via connections from level to level through a micron-thick insulator film of SiO2. Yet, the conductor capacity in the chip greatly lags behind the densification of the silicon devices. Most of the area of the chip (approximately two-thirds), still serves as a platform for wiring.
Therefore, what is needed is a way to provide for flexible wiring techniques between semiconductor devices and packages while avoiding problems associated with long lead lines and potentially shorted devices. Additionally, universality of the package, where the package can be used to package a variety of different semiconductor devices, is desirable.